RS20060554A - Preparation of syngas for acetic acid synthesis by partial oxidation of methanol feedstock - Google Patents

Abstract

A method for the production of syngas from methanol feedstock is disclosed. The methanol feed (110) is supplied to a partial oxidation reactor (112) with oxygen (114) and optionally steam (116) to yield a mixed stream (118) of hydrogen, carbon monoxide, and carbon dioxide. The carbon dioxide (122) is separated out and the hydrogen and carbon monoxide mixture (124) is fed to a cold box (126) where it is separated into hydrogen-rich and carbon monoxide-rich streams (130, 128). The separated carbon dioxide (122) can be recycled back to the partial oxidation reactor (112) as a temperature moderator if desired. The carbon monoxide-rich stream (128) can be reacted with methanol (134) in an acetic acid synthesis unit (132) by a conventional process to produce acetic acid (136) or an acetic acid precursor. Optionally, an ammonia synthesis unit (144) and/or vinyl acetate monomer synthesis unit (156) can be integrated into the plant.

Description

, , / io- iO Belgrade^

ACETEX (CYPRUS) LIMITED

OBTAINING SYNTHETIC GAS FOR THE SYNTHESIS OF ACETIC ACID BY THE PROCEDURE OF PARTIAL OXIDATION OF METHANOL

BASIS OF THE INVENTION

The present invention generally relates to a process for the preparation of hydrogen and carbon monoxide by partial oxidation of a lower alcohol by reforming, such as, for example, methanol, and more preferably to a process for the production of acetic acid from methanol that serves as a feedstock and carbon monoxide obtained by partial oxidation of methanol

In the last few years, methanol production has been increasing in countries with high gas production due to the development of high-capacity plants that use (apply) high-yield processes, such as, for example, Mega-methanol technology. The state of the market in different places can often lead to a relatively low price for methanol (in case of oversupply) and a relatively high price for natural gas (in case of a shortage of the required raw material), mainly due to its excessive use for heating buildings and houses, as well as high use in power plants. For example, in chemical plants where synthetic gas is produced to capture CO for the synthesis of acetic acid, high costs can make the cost of producing natural gas as a feedstock prohibitive.

The primary raw materials for the production of acetic acid are carbon monoxide (CO) and methanol. By installing the existing plant for the production of methanol in the unit for the synthesis of acetic acid, it is possible to eliminate the phase of introduction of methanol for the synthesis of acetic acid, instead of the production of methanol in situ for the synthesis of acetic acid. Installation of an existing plant for the production of methanol for the production of acetic acid is known in the prior art. Representative references describing this and similar procedures are US Pat. 6, 232, 352 by Vidalin, 6, 274096 by Thiebaut et al., and 6, 353, 133 by Thiebaut et al., each of which is fully incorporated herein by reference.

In US patent no. 3,920,717, Marion describes a continuous process for the production of methanol from solid and/or liquid hydrocarbon material in a catalyst-free reaction zone using a partial oxidation reactor. In US patent no. 4,006,099, Marion et al. describe improved combustion efficiency in the non-catalytic partial oxidation of liquid hydrocarbon materials in a double ring burner. In US patent no. 4,081, 253 and 4,110,359, Marion describes a process for the production of synthesis gas, comprising H 2 and CO and having a molar ratio (H 2 /CO) of about 0.5 to 1.9 by partial oxidation of hydrocarbon-containing fuels with pure oxygen.

The use of partial oxidation reactors for reforming natural gas into synthetic gas is well known in the art. Representative references that describe partial oxidation reactors for syntenic gas production include US Pat. 2,896, 927 to Nagle et al., US Patent No. 3,920,717 from Marion; US Patent No. 3,929,429 by Crouch; and US Patent No. 4,081,253 to Merion, each of which is fully incorporated herein by reference.

The production of hydrogen from methanol using a methanol reforming catalyst alone or in conjunction with a mobile hydrogen production reactor is known in the art. The references shown describe this and similar processes including US Pat. 4,175,115 to Balli et al.; US Patent No. 4,316,880 to Jockel et al.; US patent no. 4,780,300 from Yokoyama; and US Patent No. 6, 171,574 by Judah, each of which is fully incorporated herein by reference.

The cited references describing this and other similar processes for the production of acetic acid from carbon monoxide and methanol using a carbonylation catalyst are well known in the art and include US Pat. 1,961,736 by Carlin et al.; US patent no. 3,769,329 to Paulik et al.; US patent no. 5,155,261 to Marston et al.; US patent no. 5,672,743 to Garland et al., US Pat. 5,728,871 to Joensen et al.; US patent no. 5,817,869 to Hinnenkamp et al.; US patent no. 5,877,347 and 5,877,348 to Dietzel et al.; US patent no. 5,883,295 to Sunlev et al., each of which is fully incorporated herein by reference.

The primary raw materials for the production of acetic acid vinyl acetate monomer (VAM) are ethylene, acetic acid and oxygen. Carbon dioxide is produced as an unwanted side product in the reaction and can be removed from the recycled ethylene. Significant costs for the new production of synthetic gas, methanol, acetic acid and acetic acid derivatives such as VAM represent large costs for the purchase of the necessary equipment. It would be extremely desirable for the main cost to be largely eliminated or at least significantly reduced.

As far as the applicant is aware, there is no prior art invention related to feeding methanol as a feedstock to a partial oxidation reactor to produce hydrogen and carbon monoxide for the synthesis of acetic acid. Furthermore, as far as the applicant is aware, there is no prior art described invention for modifying an existing methanol plant with partial oxidation reactors to obtain lower alcohols by reforming, for example, methanol, in the presence of carbon dioxide, oxygen, flow or a combination thereof.

THE ESSENCE OF THE INVENTION

The present invention relates to a process for obtaining synthetic gas through the partial oxidation of methanol for use when the costs of using methanol are lower compared to the costs of natural gas, and in particular to a process for obtaining acetic acid from methanol and CO, where CO is separated from the synthetic gas produced by the partial oxidation of methanol.

In one embodiment, the present invention provides a process for preparing a hydrogen-rich stream and a carbon monoxide-rich stream. The process includes (a) reacting a methanol feed stream and an oxygen-rich stream, and optionally a temperature moderator, in a partial oxidation reactor to produce a syngas stream, (b) separating the syngas stream into a carbon dioxide-rich stream and a hydrogen/carbon monoxide-containing mixed stream, and (c) separating the mixed stream into a hydrogen-rich stream and a carbon monoxide-rich stream. The process further includes a phase of vaporizing the methanol feed stream before adding it to the partial oxidation reactor. The temperature moderator may be selected from the flow, carbon dioxide, nitrogen, cooled and recycled effluent, or a mixture thereof. The temperature moderator can be a stream rich in carbon dioxide that is recycled from the outlet of that reactor. The reactor for partial oxidation can be without a catalyst and operates at temperatures between 1 lOOo and 2000oC. It is preferable that the partial oxidation reactor operates at temperatures between 1300oC and 1500oC. The process further comprises reacting a portion of the methanol feed stream with a carbon monoxide-rich stream to produce acetic acid. The process further comprises the steps of feeding a nitrogen stream from an air separation unit, and feeding a nitrogen stream and a hydrogen-rich stream to an ammonia synthesis plant to produce ammonia. The process further includes the steps of providing a flow of ethylene, and supplying a flow of ethylene, oxygen, and acetic acid to a vinyl acetate monomer synthesis plant to produce vinyl acetate monomer. The oxygen used in the reactor for partial oxidation and in the plant for the synthesis of vinyl acetate monomer is supplied via the air separation plant.

In yet another embodiment, the present invention includes a process for converting an original methanol plant into an acetic acid synthesis plant.

The process includes the steps of (a) providing an original methanol plant with at least one oxidation reactor to convert hydrocarbons into a synthesis gas stream containing hydrogen, carbon monoxide and carbon dioxide; and a closed methanol synthesis process for converting hydrogen and carbon monoxide from the synthesis gas stream to methanol; (b) feeding at least one portion of the feedstock methanol stream, oxygen from the air separation plant and. optionally, a temperature moderator, in at least one partial oxidation reactor, (c) installing a first separation plant, to separate the carbon dioxide-rich stream and the hydrogen/carbon monoxide-containing mixed stream from the syngas exit stream,

and (d) installing a second separation plant to separate the hydrogen-rich stream and the carbon monoxide-rich stream from the mixed stream, (e) installing an acetic acid synthesis plant, (f) feeding the carbon monoxide-rich stream from the second separation plant and a portion of the methanol stream as feedstock to the acetic acid plant; and (g) installing an isolation valve to isolate the closed methanol synthesis stream from the remainder of the plant. The methanol is evaporated before being added to the partial oxidation reactor. The process further comprises the steps of (h) installing an ammonia synthesis plant to react the hydrogen-rich stream with nitrogen to produce ammonia, (i) feeding at least a portion of the hydrogen-rich stream from the separation unit to the ammonia synthesis plant; and (j) feeding the nitrogen flow from the air separation plant to the ammonia synthesis plant. The method may further include the steps of installing a vinyl acetate monomer synthesis plant to react ethylene, oxygen, and acetic acid to produce vinyl acetate monomer, supplying at least a portion of the oxygen from the air sparger plant to the vinyl acetate synthesis plant; and producing a carbon dioxide-rich stream in a vinyl acetate monomer synthesis plant. The process further includes recycling the carbon dioxide-rich stream in a partial oxidation reactor.

In another embodiment, the present invention includes a process for obtaining hydrogen, carbon monoxide and acetic acid from methanol. The process comprises the steps of (a) feeding a stream of volatile methanol, an oxygen-rich stream, and optionally a temperature moderator to a catalyst-free partial oxidation reactor to form a synthesis gas stream comprising hydrogen, carbon monoxide and carbon dioxide, (b) separating a carbon dioxide-rich stream and a mixed hydrogen-carbon monoxide stream from the synthesis gas stream, (c) separating a hydrogen-rich stream and a carbon-rich stream monoxide from the mixed stream and (d) reacting the carbon monoxide-rich stream with methanol in an acetic acid synthesis plant to produce acetic acid. The process further comprises the step of recycling at least a portion of the carbon dioxide-rich stream in a partial oxidation reactor without a catalyst as a temperature moderator.

BRIEF DESCRIPTION OF THE LINE|ŽA

Figure 1 is a simplified block flow diagram for one embodiment of a process for the production of hydrogen and carbon monoxide from methanol.

Figure 2 is a simplified block flow diagram for the plant of Figure 1, where an acetic acid synthesis reactor is added to the acetic acid synthesis process.

Figure 3 is a simplified block flow diagram for the plant of Figure 2 where an ammonia synthesis reactor is added to the ammonia synthesis process.

Figure 4 is a simplified block flow diagram for the plant of Figure 2, wherein the vinyl acetate monomer production reactor is added to the vinyl acetate monomer synthesis process.

Figure 5 is a simplified block flow diagram for the plant of Figure 3, where the vinyl acetate monomer production reactor is added to the vinyl acetate monomer synthesis process.

Figure 6 is a simplified block flow diagram for an alternative embodiment of the present invention for producing hydrogen and carbon monoxide from methanol where the carbon monoxide is separated and recycled in the reactor.

Figure 7 is a simplified block flow diagram for the plant of Figure 6, where the acetic acid production reactor is added to the acetic acid synthesis process.

Figure 8 is a simplified block flow diagram for the plant of Figure 7, where an ammonia production reactor is added to the ammonia synthesis process.

Figure 9 is a simplified block flow diagram for the plant of Figure 7, where the vinyl acetate monomer production reactor is added to the vinyl acetate monomer synthesis process.

Figure 10 is a simplified block flow diagram for the plant of Figure 8, where the vinyl acetate monomer production reactor is added to the vinyl acetate monomer synthesis process.

DESCRIPTION OF THE INVENTION

Detailed descriptions of the implementation of the present invention are described in the following text. However, it is understood that the above-mentioned embodiment represents only an illustration of the present invention, which may take various forms. The specific structural and functional details described herein are not limiting, but merely examples that may be modified within the scope of the claims presented.

The plant for the methanol reforming process in the partial oxidation reactor for the production of synthetic gas can be a new plant, or preferably a modification of an existing methanol plant that includes at least one partial oxidation reactor.

The present invention includes a solution to the problems associated with the production of synthetic gas from natural gas when natural gas costs are high. When such economic conditions exist, plants built for the synthesis of methanol and acetic acid can be reconfigured to produce acetic acid using existing methanol supplies as the reactor feedstock, instead of natural gas.

The conversion of methanol to carbon monoxide and hydrogen is generally shown by the following reactions:

CH30H - CO + 2H2

CH30H + H20 - 3H2 + CO2

If necessary, carbon monoxide production can be increased through a reverse displacement reaction where carbon dioxide and hydrogen react to form carbon monoxide and water.

C02 + H2-- C0 + H20

Referring to Figure 1, the process relates to the partial oxidation of a methanol stream to produce a syngas stream which can then be separated into hydrogen (H2) and carbon monoxide streams. Methanol stream 110 is fed (transferred) to a catalyst-free partial oxidation (POX) reactor 112 from an existing methanol synthesis plant, where it is combined with oxygen 114 and optionally stream 116. Methanol stream 110 is preferably purified or commercially available methanol that is purified by distillation or some other conventional process. Oxygen 114 is obtained from the air separation unit (ASU) 11, from which it is transported with compressed air. Flow 116 is preferably obtained using existing facilities. Nitrogen and excess oxygen (not shown) obtained in ASU 11 can be provided for control. If the supply of oxygen 114 used in the process is not limited, crude methanol 110 can be fed into the reactor at room temperature. However, if the oxygen supply 114 is not limited, the methanol 110 can be preheated and/or vaporized (not shown) before being fed to the POX reactor 112. When room temperature methanol 110 is added to the partial oxidation reactor 112 containing excess oxygen, the hydrogen content of the syngas outlet stream 118 is reduced.

In the POX reactor 112, a synthesis gas output stream consisting of H 2 , CO and CO 2 can be produced. The outlet stream 118 is generally cleaner than the synthesis gas produced from the natural gas fed to the reactor as more impurities are removed during the synthesis of the methanol feed stream 110. The outlet stream 118, after cooling, may be fed to a C02 separation plant, 110 which produces a C02-rich stream 122 and a CO/H2 mixed stream 124 without the presence of C02. A C0 2 -rich stream 122 is suctioned and a mixed CO/H 2 stream 124 is fed to a separation plant 126 .

The separation plant 126 preferably includes a molecular sieve and a conventional cooling chamber. The separation plant 126 splits the mixed stream 124, at least into a CO-rich stream 128 and an H2-rich stream, 130, but it also includes insignificant amounts of stream of one or more residual or exhaust gases formed by mixing H2 and CO, which can be used as fuel or can be removed from the process (not shown). The flow rich in CO 128 and the flow rich in H2 130 , can be used in alternative processes, such as, for example, plants for the synthesis of acetic acid or plants for the synthesis of ammonia, which are described in the further part of the text.

As shown in Figure 2, the CO-rich stream 128 can also be used in the acetic acid synthesis plant 132 where it is combined with the methanol stream 134, which is obtained from the same material used in the POX reactor 112. The acetic acid synthesis plant 132 consists of conventional equipment for the production of acetic acid using a well-known methodology for obtaining acetic acid 136 from CO via flow 128 and methanol via flow 134, from one or more of the aforementioned patents describing manufacturing processes that are commercially available to those skilled in the art.

For example, the conventional BP/Monsanto process can be used, or the improved BP/Monsanto process using BP-Cativa technology (iridium catalyst), so-called "

Celanese "water treatment technology, the so-called "Millennium" water treatment technology (rhodium-phosphorus oxide catalyst) and/or a two-part process of methanol carbonylation and methyl formate isomerization. The reaction generally includes reactive methanol, methyl formate, or a combination thereof in the presence of a reaction mixture containing carbon monoxide, water, a solvent, and a catalyst system that includes at least one halogenated promoter and at least one rhodium, iridium compound, or a combination of said compounds.

The reaction mixture preferably has a water content of up to 20 percent by weight. When the reaction involves simple carbonylation, the water content of the reaction mixture is preferably from 14 to about 15 weight percent. When the reaction comprises the carbonylation of water, the water content of the reaction mixture is preferably from 2 to about 8 weight percent. When the reaction involves isomerization of methyl formate or a combination of isomerization and carbonylation of methanol, the reaction mixture preferably contains an amount of water slightly greater than zero and preferably 2 percent by weight.

The process shown in Figure 3 optionally includes an ammonia synthesis plant 144, which is constructed to use H2 from syngas stream 118 and nitrogen from ASU 111. All portions of hydrogen stream 130 from CO/H2 separation plant 126 react with nitrogen flow 142 from air separation plant to form ammonia which accumulates in stream 146. Ammonia output from the synthesis plant 144 is increased by increasing hydrogen, or by adding another ammonia synthesis plant (not shown).

The process shown in Figure 4 includes, optionally, a vinyl acetate monomer (VAM) synthesis plant, 156. A portion of acetic acid from line 136 is added via line 150 to a VAM synthesis plant 156, where it reacts with ethylene 152 via line 154 and with at least one portion of oxygen 113 from an air separation plant 111. A liquid stream 158 is prepared in a conventional VAM distillation plant, 160 to produce purified (commercial specification) VAM via line 162. Carbon dioxide obtained as a byproduct of the VAM synthesis process is separated from the reactor off-gas stream via a conventional CO2 removal system (not shown), and via line 164 is recycled to the POX reactor 112.

The production of VAM is mainly achieved by acetoxylation of ethylene according to the reaction:

The main by-product is CO2, which is formed by the reaction:

Thanks to the selectivity of this process, approximately 7-8% CO2 per unit weight is produced. The plant for the production of vinyl acetate monomer, VAM, produces approximately 100,000 metric tons (MTY) of VAM per year, which requires approximately 35,000 MTY (metric tons per year) of ethylene, while also producing between 9,000 and 10,000 MTY (metric tons per year) of C02.

As shown in Figure 5, the vinyl acetate synthesis plant 156 is added to the existing acetic acid synthesis plant 132 and ammonia synthesis plant 144 for optimal utilization of the synthesis gas flow. In the VAM synthesis plant 156, a portion of the acetic acid flow 136 for monomer synthesis is added via line 150. Raw VAM via line 158 exits VAM synthesis plant 156 and enters distillation plant 160 to produce final stream 162. Carbon dioxide obtained as a byproduct of the VAM synthesis process is separated from the reactor off-gas stream via a conventional CO2 removal system (not shown), and via line 164 is recycled to POX reactor 112.

As shown in Figure 6, the entire amount or portion of carbon dioxide 222 produced and separated from the syngas outlet stream 218 is recycled in the POX reactor 212. The methanol stream 210 is fed to the partial oxidation (POX) reactor of the existing methanol synthesis plant, where it is combined with oxygen 214 and carbon dioxide 222. The methanol stream 210 is optionally methanol which is first purified by distillation or some other common process (not shown). Oxygen 214 obtained from the pre-existing air separation unit (ASU) 211 is charged with compressed air. Carbon dioxide 222 is produced in the methanol purification process 210 and can be recycled in reactor 212. POX reactor 212 produces a synthesis gas output stream 218 consisting of H 2 , CO and CO 2 . The outlet stream 218 is generally cleaner than the synthesis gas produced from the natural gas fed to the reactor as more impurities are removed during synthesis of the feed stream. After cooling, the outlet stream 218 can be fed to a C02 separation plant, 220 which produces a C02-rich stream 222 and a mixed CO/H2 stream 224 without the presence of C02. The C02-rich stream 222 can be recycled to the POX reactor 212 and the mixed CO/H2 stream 224 is fed to the separation plant 226. Recycling the C02-rich stream to the POX reactor can increase CO production by approximately 5-10% and decrease hydrogen production by approximately 3-8%. When C02 is recycled in a POX reactor, the need for methanol is reduced as a result for a given production volume.

The separation plant 226 preferably includes a molecular sieve and a conventional cooling chamber. In the separation plant 226, the mixed flow 224 is split into at least a CO-rich flow 228 and an H2-rich flow 230, but also includes insignificant amounts of flow from one or more residual or exhaust gases formed by mixing H2 and CO, which can be used as fuel or can be removed from the process (not shown).

As shown in Figure 7, the CO-rich stream 228 can be combined with stoichiometric amounts of crude methanol 234 to give acetic acid 236, using the synthetic procedure described earlier. As shown in Figure 8, the H2-rich stream 230 can be reacted with aztote 242 from the ASU in an ammonia synthesis plant 244 to produce ammonia 246. Alternatively, all or a portion of the H2-rich stream can be transferred as fuel or removed from the process for an alternative process (not shown).

As shown in Figure 9, the optional process vinyl acetate monomer (VAM) synthesis plant 256. A portion of acetic acid from line 236 is added via line 250 to the VAM synthesis plant 256, where it reacts with ethylene 252 via line 254 and with at least one portion of oxygen 213 from air separation plant 211. Liquid flow 258 is preparation in a conventional VAM distillation plant, 260 to produce purified (commercial specification) VAM via line 262. Carbon dioxide obtained as a by-product in the VAM synthesis process is separated from the reactor off-gas stream via a conventional C02 removal system (not shown), and via line 264 is recycled to the POX reactor 212.

As shown in Figure 10, the vinyl acetate synthesis plant 256 is added to the existing acetic acid synthesis plant 232 and ammonia synthesis plant 244 for optimal use of the synthesis gas flow. To VAM synthesis plant 256, a portion of acetic acid stream 236 is added via line 254, ethylene 252 via line 252, and oxygen from ASU 211 via line 213. Crude VAM via line 258 exits VAM synthesis plant 256 and enters distillation plant 260 to produce a final stream. 262. Carbon dioxide obtained as a by-product in the VAM synthesis process is separated from the reactor off-gas stream via a conventional CO2 removal system (not shown), and via line 264 is recycled to the POX reactor 212.

Standard elements of the system (not shown), which in most cases include a system for evaporation, cooling water, compressed air and the like, are supplied from the existing plant for the production of methanol and can be used in associated processes, such as, for example, plants for the synthesis of acetic acid and ammonia.

The steam generated from the regenerated waste heat in the acetic acid synthesis plant 132 and/or in any other combined process plant can be used to supply or transfer steam to the water pump (not shown), the ASU compressor 111, the POX reactor 112, the CO2 removal plant 120, and the like.

Partial oxidation reactors can be evacuated, flowless, non-catalytic gas generators into which preheated hydrocarbon and oxygen are fed.

The temperature moderator can optionally be brought into the reactor as well. The outlet stream from the partial oxidation reactor is then cooled, and optionally cleaned to remove soot and other impurities, and can then be further used or separated for additional use in the lower part of the reactor. When hydrogen gas is desired as an end product in the process, as is the case for example in ammonia synthesis reactors, temperature change converters can be used to convert CO and water vapor to hydrogen and CO 2 . When carbon monoxide is the desired end product of the reaction, as is the case in acetic acid synthesis reactors, any amount of C02 can be removed and recycled to the reactor to increase CO production, or backwash reactors are used to convert C02 and H2 to CO and H20.

When using a partial oxidation reactor from an existing methanol plant, a burner (furnace) is added for operations with crude methanol. The temperature in the partial oxidation reactor can be in the range of 1100-2000oC (2000o-3600oF) preferably 1300o-1500oC (2400o-2700oF). The pressure in the reactor can be maintained between 2 and 6 MPa, preferably around 4 MPa.

Syngas production from carbon-based liquids and solids can often result in the presence of many undesirable impurities, such as, for example, CO2, SO2, COS, CH4, Ar, N2, H20, and NH3. When natural gas is used as a feedstock for syngas production, a desulfurization/absorption plant with a catalyst bed, such as a nickel/molybdenum catalyst, can be used to remove sulfur from the process feedstock before it is fed to the reactor.

Because the natural gas used in methanol synthesis has already been desulfurized and the methanol has already been purified by distillation or some other common purification process, many of the impurities normally present from the synthesis process with natural gas are effectively eliminated from the synthesis gas.

The outlet stream obtained by the partial oxidation process has a molar ratio of H2-C02 to CO + C02 (referred to in this application as the "R ratio") ((H2-C02)/(CO+C02)) which is optimal for CO production. It is generally desirable for methanol production to have an R ratio of approximately 2.0. For the synthesis of high CO, H2 synthesis gas, the CO ratio can be from 1.5 to 3, and preferably between 1.5 and 2. Appropriate temperature moderators are added to the reaction zone and include H20, C02 and N2 from the air separation plant, the cooled and recycled gas (outflow), and their mixtures. the temperature moderator includes a portion of C02 which is cooled and separated from the outlet stream of the partial oxidation reactor and recycled again in the reactor. When steam is used as a temperature moderator, flow control can limit or prevent soot production in the reactor.

In a C02 removal plant, the output stream is separated into a C02-rich stream and a CO2-low stream, using conventional C02 separation equipment and methodology, such as, for example, an absorption/desorption process with solvents such as water, methanol, aqueous solutions of alkanolamines such as ethanolamine, diethanolamine, methyldiethanolamine, and the like, aqueous solutions of basic carbonates such as sodium and potassium carbonates, and the like. The mentioned processes are commercially available under the trade names Girbotol, Sulfinol, Rectisol, Purisol, Fluor, BASF(aMDEA) and the like.

The low C02 stream mainly contains CO and hydrogen and can be separated in a CO separation plant into CO and hydrogen rich streams. The separation plant comprises any equipment and/or methodology known in the art to separate the CO and hydrogen mixture into streams having a relatively low CO and hydrogen content, such as, for example, semipermeable membranes, cryogenic fractionation, or the like. Cryogenic fractional distillation is preferred, which includes simple partial condensation without the presence of any column, with the free choice of a pressure vibration absorption (PSA) plant and a compressor for hydrogen recycling, or methane washing. Partial condensation with columns is usually sufficient to obtain CO and hydrogen of sufficient purity for the production of acetic acid and ammonia, with minimal equipment maintenance and operating costs. If necessary, a PSA plant and a hydrogen recycle compressor can be added to the process to increase the purity of the hydrogen and the volume (rate) of CO production. For acetic acid production, the CO stream preferably contains less than 1000 ppm hydrogen and less than 2 mole percent nitrogen plus methane. To produce ammonia, the hydrogen stream is sent to a nitrogen scrubber (not shown) which preferably contains at least 80% hydrogen, and more preferably contains at least 95 mole % hydrogen.

Example 1. A stream of crude methanol is fed to a partial oxidation reactor to regenerate hydrogen and carbon monoxide. The methanol flow is fed at a rate of 1438 kmol/hour, where it combines with 719 kmol/hour of oxygen and 884 kmol/hour of steam. The partial oxidation reactor operates at approximately 1300oC (2372oF) and 4 MPa, producing a syngas outlet stream. Carbon dioxide can be removed from the syngas stream, producing a carbon dioxide-rich stream and a carbon dioxide-rich stream containing carbon dioxide and hydrogen. The carbon dioxide-rich flow can be suctioned or collected. The low carbon dioxide stream is fed to a cooling chamber where the hydrogen and carbon dioxide components are separated, yielding 1045 kmol/hr of carbon dioxide and 1812 kmol/hr of hydrogen.

Example 2: A stream of crude methanol is fed to a partial oxidation reactor to regenerate hydrogen and carbon monoxide. The methanol flow is fed at a rate of 1438 kmol/hour, where it combines with 719 kmol/hour of oxygen, 350 kmol/hour of water vapor and 296 kmol/hour of carbon dioxide recycled from the reactor outlet. The partial oxidation reactor operates at approximately 1400oC (2552oF) and 4 MPa, producing a syngas outlet stream. Carbon dioxide can be removed from the syngas stream in known ways, producing a carbon dioxide-rich stream and a carbon-dioxide-rich stream for carbon dioxide and hydrogen. The carbon dioxide-rich stream is recycled to the partial oxidation reactor at a rate of 296 kmol/hour. The low carbon dioxide stream is fed to a cooling chamber where the hydrogen and carbon dioxide components are separated, yielding 1045 kmol/hr of carbon dioxide and 1812 kmol/hr of hydrogen.

Example 3. Production of acetic acid from a plant that has operational conditions from example al. A stoichiometric amount of methanol (1045 kmol/hr) is added to a carbon dioxide-rich stream (1045 kmol/hr) in an acetic acid synthesis plant to produce 1045 kmol/hr of acetic acid.

Example 4 Production of acetic acid from a plant operating under the operating conditions of Example 2. A stoichiometric amount of methanol (1134 kmol/hr) is added to a carbon dioxide-rich stream (1134 kmol/hr) in an acetic acid synthesis plant to produce 1134 kmol/hr of acetic acid.

The invention has been described above with respect to specific examples and embodiments. The limits and limitations of the invention are not determined by the above invention, which is only illustrative, but should be determined based on the entire scope and spirit of the patent claims herein. Various modifications will be apparent to those skilled in the art, given the description and examples provided. The intention is to thereby cover all changes within the scope and spirit of the said patent claims.

Claims (18)

1. A process for obtaining a flow rich in hydrogen and a flow rich in carbon monoxide, indicated by the fact that it includes: the reaction of the feed flow of methanol and oxygen, and according to the free choice of a temperature moderator, in a reactor for partial oxidation to obtain a flow of synthetic gas; separating the syngas stream into a carbon dioxide-rich stream and a hydrogen/carbon monoxide-containing mixed stream, and separating the mixed stream into a hydrogen-rich stream and a carbon monoxide-rich stream. 2. The method according to patent claim 1, characterized in that the said method includes the evaporation of the feed flow of methanol which is fed into the reactor for partial oxidation. 3. The method according to patent claim 1, characterized in that the temperature moderator is selected from water vapor, carbon dioxide, nitrogen, cooled and recycled outlet stream or their mixtures. 4. The method according to patent claim 1, characterized in that the temperature moderator is a flow rich in carbon dioxide that is recycled from the outlet flow of the reactor. 5. The method according to patent claim 1, characterized in that the reactor for partial oxidation does not contain a catalyst and that it operates at temperatures between 1100oC and 2000oC. 6. The method according to patent claim 1, characterized in that the partial oxidation reactor operates at temperatures between 1300o and 1500oC. 7. The process of claim 1, wherein said process further comprises reacting a portion of the methanol feed stream with a stream having a high carbon monoxide content to produce acetic acid. 8. The method of claim 1, further comprising: feeding the nitrogen stream from the air separation unit, and feeding the nitrogen stream and the hydrogen-rich stream to the ammonia synthesis plant to produce ammonia. 9. The method of claim 7, further comprising: providing a flow of ethylene, and supplying a flow of ethylene, oxygen, and acetic acid to a vinyl acetate monomer synthesis plant to produce vinyl acetate monomer. 10. The method according to patent claim 9, indicated by the fact that the oxygen is fed through the air separation plant into the partial oxidation reactor and the vinyl acet monomer synthesis plant. 11. A process for converting an original methanol plant into an acetic acid synthesis plant, wherein said process comprises the steps of: converting hydrocarbons into a synthesis gas stream containing hydrogen, carbon monoxide and carbon dioxide in an original methanol plant with at least one oxidation reactor; conversion of hydrogen and carbon monoxide from the flow of synthetic gas into methanol in a closed process for the synthesis of methanol; feeding at least one portion of the methanol feed stream, oxygen from the air separation plant and optionally a temperature moderator, to at least one partial oxidation reactor, installing a first separation plant to separate the carbon dioxide-rich stream and the hydrogen/carbon monoxide-containing mixed stream from the syngas outlet stream, and installing a second separation plant to separate the hydrogen-rich stream and the carbon monoxide-rich stream from the mixed stream; installing a plant for the synthesis of acetic acid; feeding the carbon monoxide-rich stream from the second separation plant and a portion of the methanol stream as feedstock to the acetic acid synthesis plant; and installing isolation valves to isolate the closed methanol synthesis stream from the rest of the plant. 12. The method according to claim 11, characterized in that the methanol evaporates before it is added to the reactor for partial oxidation. 13. The method of claim 11, further comprising: installing an ammonia synthesis facility for reacting the hydrogen-nitrogen-rich flow to produce ammonia; feeding at least one portion of the hydrogen-rich stream from the separation unit to the ammonia synthesis plant; and feeding nitrogen flow from the air separation plant to the ammonia synthesis plant. 14. The method according to patent claim 11, characterized in that it includes: installing a plant for the synthesis of vinyl acetate monomer for the reaction of ethylene, oxygen, and acetic acid to obtain vinyl acetate monomer; feeding at least one portion of oxygen from the air spearing plant to the vinyl acetate synthesis plant; and producing a carbon dioxide-rich stream in a vinyl acetate monomer synthesis plant. 15. The method of claim 14 further comprising recycling the carbon dioxide-rich stream in a partial oxidation plant. 16. A process for obtaining hydrogen, carbon monoxide and acetic acid from methanol, characterized by the fact that it includes the stages of: supplying a flow of volatile methanol, oxygen, and optionally, a temperature moderator, to a reactor for partial oxidation without a catalyst to form a flow of synthetic gas that includes hydrogen, carbon monoxide and carbon dioxide; separating the carbon dioxide-rich flow and the mixed flow of hydrogen and carbon monoxide from the synthetic gas flow; separating the hydrogen-rich stream and the carbon monoxide-rich stream from the mixed stream and reacting the carbon monoxide-rich stream with methanol in an acetic acid synthesis plant to produce acetic acid. 17. The method according to claim 12, characterized in that it further comprises the method of recycling at least a portion of the flow rich in carbon dioxide in the reactor for partial oxidation as a temperature moderator. 18. The method according to patent claim 12, characterized in that the temperature moderator is water vapor.